Option Meaning
s/pattern/substitution/g Replace all matches of pattern.
s/pattern/substitution/i Ignore case in matching.
s/pattern/substitution/e Evaluate substitution as an expression.
s/pattern/substitution/o Compile expression only once.
s/pattern/substitution/m Allow ^ to match after every newline and $ to match before every newline in the string being searched.
s/pattern/substitution/s Allows a period to match a newline.